Issue 2351 - Add a custom menu item for whitelisting the current site

mobile/android/base/resources/menu/browser_app_menu.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
 
     <item android:id="@+id/reload"
           android:icon="@drawable/ic_menu_reload"
           android:title="@string/reload"/>
@@ skipping 25 matching lines @@
     <item android:id="@+id/save_as_pdf"
           android:title="@string/save_as_pdf" />
 
     <item android:id="@+id/find_in_page"
           android:title="@string/find_in_page" />
 
     <item android:id="@+id/desktop_mode"
           android:title="@string/desktop_mode"
           android:checkable="true" />
 
+    <item android:id="@+id/block_ads"
+          android:title="@string/block_ads"
+          android:enabled="false"
+          android:checkable="true" />
+
     <item android:id="@+id/addons"
           android:title="@string/addons"/>
 
     <item android:id="@+id/downloads"
           android:title="@string/downloads"/>
 
     <item android:id="@+id/apps"
           android:title="@string/apps"/>
 
     <item android:id="@+id/char_encoding"
           android:visible="false"
           android:title="@string/char_encoding"/>
 
     <item android:id="@+id/settings"
           android:title="@string/settings" />
 
     <item android:id="@+id/help"
           android:title="@string/help_menu" />
 
     <item android:id="@+id/new_guest_session"
           android:icon="@drawable/ic_menu_guest"
           android:visible="false"
           android:title="@string/new_guest_session"/>
 
     <item android:id="@+id/exit_guest_session"
           android:icon="@drawable/ic_menu_guest"
           android:visible="false"
           android:title="@string/exit_guest_session"/>
 </menu>